Track lighting systems wherein lighting fixtures are mounted to tracks and supplied electrical power by busses associated with the track are well known. The tracks are generally hollow elongated extrusions of aluminum or other suitable material. Channels are formed on the interior walls of the hollow track within which are mounted insulating carriers holding electrical busses. Typically the track will be provided with one or more voltage busses, a neutral bus, and a grounding element. The grounding element can be either a ground bus or a rib of the track extrusion. A lighting fixture is mounted to the track by way of a track adapter. Electrical contacts on the adapter contact the electrical busses carried by the track to supply power to the light fixture.
Connectors are used to supply electrical current to the track and to connect adjacent track sections. The connector has a nose portion which is snugly received within the end of the hollow track by way of an interference fit to mechanically couple the connector to the track section. Electrical contacts extending from lateral surfaces of the nose of the connector contact the voltage and neutral busses and the grounding element within the track to effect electrical connections between the connector and the track section.
There are two basic types of connectors. The first type of connector, known as a "feed," has either a single nose for connecting to a single track section, or multiple noses for connecting to multiple track sections. Each nose portion has electrical contacts in electrical communication with corresponding neutral and voltage busses and a grounding element of the track. Wires connected to a source of electrical power are connected to terminals within the connector so that the feed provides the track section or sections with electrical power.
The second type of connector physically and electrically connects two or more pieces of track. The connector has a plurality of nose portions, each of which is received within an open end of a different section of track. Each nose portion has electrical contacts in electrical communication with corresponding electrical contacts of the other nose portions so as to conductively connect each track section to adjacent track sections. Unlike the feed, the connector is not connected directly to an electrical junction box. Instead one of the track sections is powered, such as by a feed connector at its opposite end, and the connector conductively connects the powered track section to one or more unpowered track sections.
Connectors used to mechanically and electrically connect adjacent track sections can come in a variety of configurations: a straight connector for connecting two adjacent collinear track sections; an L-shaped connector for connecting two track sections disposed at right angles; a T-shaped or Y-shaped connectors for joining three track sections; X-shaped connectors for connecting four track sections; and flexible connectors which can be bent to joint two adjacent track sections at virtually desired angle.
As used herein, the term "connector" will be understood to mean any device which mechanically couples to one or more track sections of a track lighting system and either electrically connects one or more track sections to a source of electrical power or electrically connects two or more track sections to one another.
A problem with prior art connectors for track lighting systems concerns the integrity of the mechanical connection between the connector and the track section(s). Heretofore connectors have generally relied only upon the interference fit between the nose section of the connector and the interior walls of the hollow track section. Since the track sections and the connectors are supposed to be stationary once mounted to the support surface, this type of mechanical connection should in theory be adequate. In practice, however, the relatively heavy (e.g., twelve gauge) electrical wires required by many electrical codes tend to be somewhat stiff. Thus, after the installer makes the electrical connections to the connector and tries to stuff the excess wire back up through the hole in the support surface, the wire can exert a force which tends to push the connector away from the support surface. The same effect is sometimes achieved even after a proper initial installation by later workers relocating the wire in the course of installing other infrastructure, such as plumbing or ventilation ducts, or by making later electrical repairs. The forces exerted by the stiff wire can result in a connector which bends at an angle with respect to the track and leaves an unsightly gap between the connector and the support surface.
This problem also exists in so-called "pendant-hung" track lighting installations, where the track is not mounted directly against the ceiling but instead is suspended below the ceiling by a plurality of vertical stems. Typically an electrical conduit runs vertically along one of the stems and then makes a 90.degree. turn to run along the top of the track. The conduit then makes another 90.degree. turn to connect to a socket inside the connector. In this type of installation forces are exerted against the connector not only by the heavy gauge electrical wire but also by the conduit's resistance to turns.
Thus there is a need for a connector for track lighting systems which provides an improved physical connection between the connector and an associated track section.
There is a further need for a connector for track lighting systems which will help prevent the connector from being bent at an angle with respect to an associated track section by forces exerted by electrical wiring.
A further problem is associated with prior art connectors for track lighting systems wherein the connectors are grounded to the track extrusion. To accomplish this ground connection a ground contact extends laterally from the nose portion of the connector to contact a rib of the track. The ground contact is constructed from copper, brass, or other suitable conductive material and is typically spring-loaded to ensure good electrical coupling between the contact and the rib of the track. Providing the connector with a spring-loaded ground contact increases the cost and complexity of the manufacturing process. Similarly, providing the track with a special rib whose sole purpose is to provide a structure for engaging the ground contact of the connector adds to the complexity and cost of the track.
Thus there is a need for a connector for track lighting systems which eliminates the need for a spring-loaded ground contact.
There is a further need for a connector for track lighting systems which eliminates the need for a special structure on the track to which the ground contact can electrically couple.